This invention relates to a novel fluid composition and a fluid for traction drive which contains this composition. More particularly, it relates to a fluid composition which contains o-tercyclohexyl compound and has good stability at low temperatures and a fluid for traction drive which contains this fluid composition.
Recently, traction driving devices using a fluid are used in place of the hitherto used gears as automatic transmission devices of rotary drive power in automobiles, etc., variable transmission devices of machines, constant speed transmission devices of aircraft parts and transmission devices of rotary drive power in land and water vehicles.
The fluids used for such traction driving devices are required to have characteristics such as smaller change between the properties under low temperature condition, e.g., at starting of engine and the properties (e.g., traction coefficient) under the subsequent high temperature condition.
Hitherto, mineral oils have been used as a fluid for traction drive, but use of synthetic oils have been proposed in view of the characteristics having high traction coefficient.
For example, Japanese Patent Publication (Kokoku) No.339/71 (corresponding to U.S. Pat. No. 3440894 of Monsanto Company) discloses an invention relating to a fluid for traction drive (tractant) wherein it is suggested that tercyclohexyl compound can be used as a traction drive. This tercyclohexyl compound has many isomers, most of which are solid at room temperature and so, when it is used as a fluid for traction drive, generally, a mixture of two or more of tercyclohexyl compounds is used as fluid composition.
However, according to the inventors' study, it has been found that when a fluid for tranction drive comprising a mixture of a plurality of tercyclohexyl compounds is stored for an extended period of time at low temperatures, crystals of tercyclohexyl compounds are separated.
Tercyclohexyl compounds can also be used as bases for lubricants, heat transfer oils, rust preventives, insulating oils, etc. in addition to as fluids for traction drive, but in this case, too, the existing crystals cause clogging of pipings and besides the properties are apt to change.